In general, in factories where machining or assembly is performed, a programmable controller is used to control a machining cell, which is a unit formed by combining a machine tool, an industrial robot, etc. Furthermore, the entire production system is often composed of a plurality of programmable controllers, though it depends on the system scale, and the programmable controller for each machining cell is interconnected to the other programmable controllers via a communication network, such as Ethernet (registered trademark) or FL-NET, thereby performing communication among the programmable controllers.
When the processing performed in respective machining cells is the same, as a method of transferring a sequence program to the programmable controllers interconnected as described above, the method disclosed in Japanese Unexamined Patent Application, Publication No. H5-297902 (“JP '902”) is known, for example. JP '902 discloses that a program maintenance tool connected to a plurality of programmable controllers via a transmission line has a multiplexing determination function for determining whether a specified programmable controller is multiplexed with other programmable controllers, and transfer of a sequence program to the respective multiplexed programmable controllers is collectively performed through a single operation.